Post by oldchopperguy on Jul 9, 2009 0:12:10 GMT -5
Quick wrap-up... I did get "Lil' Bubba" running well again, in fact, better than ever. End of story is that both the CDI and coil started going bad immediately after installing the new carb! Does that suck, or what?
After installing a new Bando coil and "New Racing" CDI (same unit as in the "Free CDI" post) I had proper spark, better advance, no rev-limiter, and could stop trying to correct the electronic problems I didn't know I had, through carb tuning... OK, Rebs, we've all done SOMETHING that dumb now, haven't we?...
My individual engine simply would NOT run right with the factory "snorkel" to the airbox area under the seat. Never did, never will. The carb would NOT tune no matter what. I wasted WEEKS on it before trying tuning sans air-filter and snorkel... If your scoot has one of these snorkels, and you've tried EVERYTHING and still can't get your carb right, try tuning it with NO air filter or extension, THEN put on the little Uni "sock" filter. You may find it is THE fix!
The final setup ended up with the carb jetted 42.5 on the idle and 110 on the main. The needle had to be raised a full 2 notches higher than the highest factory notch, as/per the pix in the post. Any lower, and the acceleration bogged.
The idle-air mix screw is approx. 3 turns from bottomed. The air-filter turned out to be THE most critical part of the entire process, along with the needle setting. It is now a UNI "sock" filter fitted directly to the carb throat. My engine and carb simply won't run right with ANY extension to an air-filter, and this sock filter is the closest thing to no filter at all. It runs like gang-busters.
FINALLY... I have instant starting, smooth idle, strong (REALLY strong) acceleration from idle to 8,200 rpm, and I don't think the engine is going to run any better until I can install a better exhaust (which will no doubt reqire another slightly richer main jet) but after this 6-week nightmare, that is NOTHING! I can now change jets in about 3 minutes, blindfolded!
With the engine finally right, it runs strong up to 52 mph top end, at 8,200 rpm. NOW... to get the lower rpm cruise, and a little more top end, I'm going to have to work on the CVT/variator.
Jr and Kliff have been real loyal troopers for me, and their advice is golden!
I'm saving my pennies now for the same variator Jr is testing. His tests are MOST encouraging!
My scoot is very similar to the Sunl, Roketa, Tank, etc. so much of what I learned may be good groundwork for others with these GY6 150's (ESPECIALLY if you have the big, ribbed snorkel intake). Above all, the needle height and intake/air-filter were the CRITICAL elements, and the ones that gave the most grief with trial and error.
As for the electronics, the better CDI with no rev-limiter helped NOTICEABLY, and the Bando coil actually made enough improvement over stock, that I had to slow the idle nearly 1,000 rpm!
Currently my exhaust and spark plug are still original stock, so there is room for improvement there too, but now, in anything up to 50 mph traffic, I can "sh*t n' git" and match speed with the cagers in short order. SWEET!!! For better high-speed riding convenience, the tranny must now be massaged to get the end result I'm wanting; more top-end, faster cruising and lower rpm.
Hope this wrenching may encourage and guide other Rebs with similar scoots! When these beasties go wrong, (or if they just weren't quite "right" from the factory...) you just have to break out the Vice-Grips and duct tape and have at'em...
Enjoy the ride!
Leo in Texas
After installing a new Bando coil and "New Racing" CDI (same unit as in the "Free CDI" post) I had proper spark, better advance, no rev-limiter, and could stop trying to correct the electronic problems I didn't know I had, through carb tuning... OK, Rebs, we've all done SOMETHING that dumb now, haven't we?...
My individual engine simply would NOT run right with the factory "snorkel" to the airbox area under the seat. Never did, never will. The carb would NOT tune no matter what. I wasted WEEKS on it before trying tuning sans air-filter and snorkel... If your scoot has one of these snorkels, and you've tried EVERYTHING and still can't get your carb right, try tuning it with NO air filter or extension, THEN put on the little Uni "sock" filter. You may find it is THE fix!
The final setup ended up with the carb jetted 42.5 on the idle and 110 on the main. The needle had to be raised a full 2 notches higher than the highest factory notch, as/per the pix in the post. Any lower, and the acceleration bogged.
The idle-air mix screw is approx. 3 turns from bottomed. The air-filter turned out to be THE most critical part of the entire process, along with the needle setting. It is now a UNI "sock" filter fitted directly to the carb throat. My engine and carb simply won't run right with ANY extension to an air-filter, and this sock filter is the closest thing to no filter at all. It runs like gang-busters.
FINALLY... I have instant starting, smooth idle, strong (REALLY strong) acceleration from idle to 8,200 rpm, and I don't think the engine is going to run any better until I can install a better exhaust (which will no doubt reqire another slightly richer main jet) but after this 6-week nightmare, that is NOTHING! I can now change jets in about 3 minutes, blindfolded!
With the engine finally right, it runs strong up to 52 mph top end, at 8,200 rpm. NOW... to get the lower rpm cruise, and a little more top end, I'm going to have to work on the CVT/variator.
Jr and Kliff have been real loyal troopers for me, and their advice is golden!
I'm saving my pennies now for the same variator Jr is testing. His tests are MOST encouraging!
My scoot is very similar to the Sunl, Roketa, Tank, etc. so much of what I learned may be good groundwork for others with these GY6 150's (ESPECIALLY if you have the big, ribbed snorkel intake). Above all, the needle height and intake/air-filter were the CRITICAL elements, and the ones that gave the most grief with trial and error.
As for the electronics, the better CDI with no rev-limiter helped NOTICEABLY, and the Bando coil actually made enough improvement over stock, that I had to slow the idle nearly 1,000 rpm!
Currently my exhaust and spark plug are still original stock, so there is room for improvement there too, but now, in anything up to 50 mph traffic, I can "sh*t n' git" and match speed with the cagers in short order. SWEET!!! For better high-speed riding convenience, the tranny must now be massaged to get the end result I'm wanting; more top-end, faster cruising and lower rpm.
Hope this wrenching may encourage and guide other Rebs with similar scoots! When these beasties go wrong, (or if they just weren't quite "right" from the factory...) you just have to break out the Vice-Grips and duct tape and have at'em...
Enjoy the ride!
Leo in Texas